New dinghy handicap with lap

I don't know if i'm being dim, but I don't understand what thr problem is that you are trying to solve. Seems to be a formula that ensures that lapped slower boats place bbadly. Why?

No you're not being dim.

A Mirror which does  5 laps in 1500 seconds is taking 300 seconds per lap. It is therefore reasonable to expect that if it was allowed to do another lap (i.e. sail the same distance as the Laser) this would also take around 300 seconds, giving a total race time of 1800 seconds.
If the Laser has taken 1695 seconds to do this same distance (i.e. less than two minutes faster), it should be beaten by miles on handicap by the Mirror which is a much slower boat.

Working backwards through the "improved" formula would give an estimated time for the Mirror to compete the same distance as the laser of 2160 seconds, which implies that the sixth lap would take nearly twice as long as all the previous ones. Unless the Mirror capsizes, this would be extremely unlikely.

One correction factor which can make average lap calculation fairer is to use the ratio of times between laps for the boats which did more laps as the multiplier for the slow boats, instead of the fixed ratio of distances. This helps to compensate for changes in conditions.

A typical example would be an evening race where the fastest boats end up doing their extra lap in much less wind than the slower boats. Say the Laser does lap 1 in 20 mins, lap 2 in 20 mins and lap 3 in 40 mins because the wind drops really badly after about 50 mins of racing. If the Mirror did lap 1 in 25 mins and lap 2 in 26 mins, and then finished just as the wind dropped, it would beat the Laser by miles if it was averaged up by distance sailed.

If the Mirror had carried on for three laps, it's likely that its last lap would also have taken twice as long so this method can counteract for this. It does need quite a bit of 'manual input' and a reasonably large sample of boats though to ensure that boats which capsized, or otherwise changed speed for reasons other than the conditions changing can be excluded when working out the ratio of lap times though.

Is it fairer that a boat does less laps?

What if you wanted to finish some laser on 5 laps where some where doing 6 you can't cause of handicap and times this formula resolves that situation. What I have done is make sailing have a fairer playing field. At my club if all boats did same number of laps different results would of taken place. If you actually look at my formula handicaps still play a part but the correct is dependent on number of laps sailed makes it fairer

Now your point about extra laps. The thing that stuffs up handicap racing in variable conditions above all else is long laps. Ideally all laps should be short enough so all boats start and finish together - clearly impossible, but if the slow boats aren't doing 4 or 5 laps in varying conditions anomalies are inevitable.

But I still don't see what your formula does that's useful. I suggest you work through it again, using the two boats that should dead heat concept, and factor in both increasing and decreasing last lap breeze to give yourself a full picture of what goes on.

Originally posted by Dches Is it fairer that a boat does less laps

Yes, of course. The number of laps a boat completes is a function of how quick the class is, not how good the sailor is.

Part of he art of good race management in a series with varying winds is to juggle your S flags so that different classes finish first each week, and different classes get to finish late each week. On evening races we have our start times juggled so the most numerous classes all tend to cross the finish line together.